Electrical and structural properties of AlGaN: A comparison with CVD diamond

The present state of the AlGaN system is discussed in comparison to the known properties of CVD diamond. Growth and structural features of thin films as well as heterostructures are described. The variation of the fundamental optical gap with aluminum content provides the basis for the application of AlGaN in optical devices for the ultraviolet spectral range. The large conduction band offset between GaN and AlN together with reasonable dopability of AlGaN allow the construction of new field effect transistors with promising performance. The use of AlGaN in surface acoustic wave devices and the potentially negative electron affinity of alloys with high Al content are also briefly mentioned.